Atrioventricular and left bundle-branch block (I44) ICD-10-CM
The I44 code range covers atrioventricular and left bundle-branch block with 13 ICD-10-CM diagnosis codes. 10 of them are billable and valid for claim submission in fiscal year 2026, and the category headers group them but cannot themselves be billed.
Codes in the I44 Range 13 codes · 10 billable
- I44 Atrioventricular and left bundle-branch blockNon-billable
- I44.0 Atrioventricular block, first degree
- I44.1 Atrioventricular block, second degree
- I44.2 Atrioventricular block, complete
- I44.3 Other and unspecified atrioventricular blockNon-billable
- I44.30 Unspecified atrioventricular block
- I44.39 Other atrioventricular block
- I44.4 Left anterior fascicular block
- I44.5 Left posterior fascicular block
- I44.6 Other and unspecified fascicular blockNon-billable
- I44.60 Unspecified fascicular block
- I44.69 Other fascicular block
- I44.7 Left bundle-branch block, unspecified
Clinical Terms in This Code Range
Definitions from the National Library of Medicine for conditions coded in the I44 range.
Accelerated Idioventricular Rhythm
A type of automatic, not reentrant, ectopic ventricular rhythm with episodes lasting from a few seconds to a minute which usually occurs in patients with acute myocardial infarction or with DIGITALIS toxicity. The ventricular rate is faster than normal but slower than tachycardia, with an upper limit of 100 -120 beats per minute. Suppressive therapy is rarely necessary.
Atrioventricular Block
Impaired impulse conduction from HEART ATRIA to HEART VENTRICLES. AV block can mean delayed or completely blocked impulse conduction.
Digitalis
A genus of toxic herbaceous Eurasian plants of the Plantaginaceae which yield cardiotonic DIGITALIS GLYCOSIDES. The most useful species are Digitalis lanata and D. purpurea.
Parasystole
A cardiac arrhythmia that is caused by interaction of two independently initiated cardiac impulses of different rates from two separate foci. Generally one focus is the SINOATRIAL NODE, the normal pacemaker. The ectopic focus is usually in the HEART VENTRICLE but can be in the HEART ATRIUM or the ATRIOVENTRICULAR NODE. Modulation of the parasystolic rhythm by the sinus rhythm depends on the completeness of entrance block surrounding the parasystolic focus.
About the I44 Code Range
ICD-10 codes I44 and its subcodes are specifically used to classify various forms of atrioventricular (AV) blocks and left bundle-branch blocks, which are types of heart conduction disorders affecting the electrical signals that control heartbeats.
These codes cover different degrees and types of AV block, including I44.0 for first degree or partial AV block, sometimes called partial atrioventricular block; I44.1 for second degree block, which includes variants like Mobitz type I and II; and I44.2 for complete AV block, also known as complete heart block or idioventricular rhythm. The category I44.3 captures other or unspecified AV blocks, such as postoperative arrhythmias. The left bundle-branch block codes include I44.4 and I44.5 for left anterior and left posterior fascicular blocks respectively, often detectable on EKGs as monofascicular or bifascicular blocks. Unspecified fascicular blocks are coded as I44.6, and I44.7 covers unspecified left bundle-branch blocks, including complete or incomplete types. These codes help medical coders precisely document conduction abnormalities that may impact heart function and treatment decisions.
Questions About This Page
How many billable codes are in the I44 range?
Of the 13 codes in this range, 10 are billable and valid for claim submission from October 1, 2025 through September 30, 2026. Category header codes group them but cannot be reported on claims.
What does the I44 range classify?
The range classifies atrioventricular and left bundle-branch block. Each code links to its own reference page with billing status, MS-DRG grouping, coding notes, and clinical information.
Related References
Source: CMS FY 2026 ICD-10-CM Tabular List and order file, effective October 1, 2025 through September 30, 2026.
